lldb debug jit-compiled code with llvm on windows

process A generate function Func1 code with llvm jit compiler, and calls Func1. modeled on “Kaleidoscope: Adding Debug Information” add debug information. how to use LLDB to attach process A to debug this function, add a breakpoint in the function?


In theory you don’t have to do anything special to debug some JIT-ed code as everything should just work (based on the gdb jit interface). In practice I tried it out a few days ago and it wasn’t working at all even in the case when the application is launched under LLDB (not with attach). LLDB was understanding the eh_frame for the JIT-ed code but didn’t found the debug info for unknown reason. We should investigate it and try to fix it sometime. We (lldb for android developers) plan to do it sometime but if you are interested in it then please feel free to take a look and let us know if you have any question.


My analysis of the code, the reasons are:

Since the debugging process is MSVC compiler, there is no DWARF debugging information. So lldb get __jit_debug_register_code and __it_debug_descriptor symbol debugging process fails, and __jit_debug_register_code not support MSVC.

I do not know whether correct?

I don’t know how JIT debugging should work on WIndows with MSVC but I don’t think LLDB support it in any way. What I wrote should be true on Linux (and on some related) systems. You might be able to get the same results on Windows if you use lli (LLVM based JIT runner) but I have no knowledge if it will work or not.

Can you also try clang-cl and see if it works?